Well, military design exercises are sort of a thing of their own. It sort of goes like this:

IF: the following assumptions aren't complete and utter horseshit

THEN: we could build you one of these if you give us enough money.

So for scale and perspective, go look at that link again and keep your eye out for a "medium intratheater transport." Imagine each one of those says "Southwest Airlines" on the side and you're at about the scale being discussed.

So that's the ridiculous part. You accept that as the boundary conditions. Then you go

"Okay, but if we give X airframe Y thrust, will it stay in the sky?"

"Okay, if we run A nuclear piles in B liquid sodium, will we get enough thrust for that last equation?"

"Okay, if those two equations balance out, can we pass the buck on everything else?"

Imagine landing it. Imagine flying it in a storm. Imagine the PR fun involved in having half a Chernobyl overhead.

Yeah, it was never going to happen. But it's kinda funny to contemplate the conditions necessary for someone to even get vaguely serious about it.